class Queue {
  constructor() {
    this.items = []
  }
  enqueue(item) {
    this.items.push(item)
  }
  dequeue() {
    return this.items.shift()
  }
  front() {
    return this.items[0]
  }
  isEmpty() {
    return this.items.length === 0
  }
  size() {
    return this.items.length
  }
  toString() {
    return this.items.join(' ')
  }
}
module.exports = {
  Queue,
}
